Recent integration of copper interconnect processes into IC (integrated circuit) manufacturing requires copper terminating chips to be bonded directly on the copper metal pad and circuit boards. The present invention allows the use of conducting polymers to bond copper terminating chips directly on copper substrate or printed circuit boards.
U.S. Pat. No. 5,923,955 to Wong describes a process for creating a flip-chip bonded combination for a first and second integrated circuits using a Ni/Cu/TiN structure.
U.S. Pat. No. 5,891,756 to Erickson describes a method for forming a solder bump pad, and specifically to converting a wire bond pad of a surface-mount IC device to a flip-chip solder bump pad such that the IC device can be flip-chip mounted to a substrate. The method uses a Ni layer over the pad.
U.S. Pat. No. 5,795,818 to Marrs describes a method of forming an interconnection between bonding pads on an integrated circuit chip and corresponding bonding contacts on a substrate. The method uses coined ball bond bumps.
U.S. Pat. No. 5,904,859 to Degani describes a method for applying under bump metallization (UBM) for solder bump interconnections on interconnection substrates. The UBM comprises a Cu, Cu/Cr, Cr multilayer structure.
U.S. Pat. No. 5,767,009 to Yoshida et al. describes a method of reducing cross talk noise between stacked semiconductor chips by the use of a chip on chip mounting structure.
U.S. Pat. No. 5,804,876 to Lake et al. describes a low contact resistance electrical bonding interconnect having a metal bond pad portion and conductive epoxy portion.
Accordingly, it is an object of the present invention is to provide a method of bonding a chip to a substrate without the need for a bump metal, wetting agents, and barrier materials.
Another object of the present invention is to provide a method of bonding a chip to a substrate avoiding the use of environmentally unfriendly solder and solder material.
An additional object of the present invention is to provide a method of bonding a chip to a substrate in smaller micron scale metal pitch sizes.
Other objects will appear hereinafter.
It has now been discovered that the above and other objects of the present invention may be accomplished in the following manner. Specifically, a semiconductor chip having an exposed metal terminating pad thereover, and a separate substrate having a corresponding exposed metal bump thereover are provided. A conducting polymer plug is formed over the exposed metal terminating pad. A conforming interface layer is formed over the conducting polymer plug. The conducting polymer plug of the semiconductor chip is aligned with the corresponding metal bump. The conforming interface layer over the conducting polymer plug is mated with the corresponding metal bump. The conforming interface layer is thermally decomposed, adhering and permanently attaching the conducting polymer plug of the semiconductor chip with the corresponding metal bump of the separate substrate. Methods of forming and patterning a nickel carbonyl layer are also disclosed.